Sealing means for electrolytic devices



May-7, 1935. F. D. SPRAGUE ET AL SEALING MEANS FOR ELECTROLYTIC DEVICES Filed NQV. 10, 1930 fiflMDEWOJVDJZWGW m mmalflqVqmm INVENTORS BY @0114 m ATTORNEYS Patented May 7, 1935 PATENT OFFICE- SEALING MEANS FOR ELECTROLYTIC DEVICES Frank Desmond Sprague and Frederick W. McNamara, North Adams, Mam, assignors to Sprague Specialties 00., Quincy, Mun, a corporation of Massachusetts 1 Application November 10, 1930, Serial No. 494,784

6Claiml.

Our invention relates to sealing means for electrolytic devices and more particularly to means providing proper sealing around electrodes projecting from such devices.

In various types of electrolytic devices, for instance, electrolytic condensers, a liquid and airtight sealing of the device is of primary importance. Not only is this required to forestall the spilling of the electrolyte, but also to prevent the salt dissolved in the electrolyte from creeping through leaks which may occur in the joints-of such devices, a phenomenon which is characteristic ofiall electrolytic apparatus and which is due to the salt rising out of the solution. In fact, creepage of the electrolyte frequently takes place through Joints which are impermeable to the liquid electrolyte. In view of the above and because of the importance of preventing contamination of the electrolyte by impurities which may enter through leaks, the requirement of perfect sealing of such devices is evident.

Our invention relates to the method of sealing for the prevention of leakage between the cover of an electrolytic device and an electrode or electrodes projecting therethrough and will be illustrated in connection with an electrolytic condenser.

Referring to the drawing which forms part of this specification, Figure 1 is a side elevation, partly in section of a electrolytic condenser embodying our invention.

Fig. 2 is an enlarged fractional view showing the sealing means forming our invention.

The condenser of Fig. 1 comprises a cylindrical container 20 of copper or other inert metal which constitutes the cathode and is provided with a cover ll of insulating material and contains a suitable electrolyte it into which project an electrode A supported by the cover I4.

The electrode A, which is of aluminum or other film-forming metal constitutes the anode of the condenser and may be of any suitable design. However, we prefer to provide anodes of the type described in the co-pending applications of F. Desmond Sprague and R. U. Clark, Ser. No. 416,939 filed December 27, 1929, now Patent No. 1,958,682, and of Max Knab, Ser. No. 441,128 of April 2, 1930, now patent 1,983,468, which possess various advantages fully described in these applications.

Such an electrode as shown in Fig. 1 consists of a tubular portion 8 provided with helical corrugations, which through a conical portion 9 extends in a stem III, the portions 8, 9 and It! being formed preferably of a single piece of metal.

The portion 0 is provided with holes 9a for the circulation of the electrolyte. The stem I0 is provided with a bevelled shoulder 2|, the purpose of which will be later explained. The stem II which is reduced beyond the shoulder 2| is threaded at its end II and carries nuts I2 and I2, which secure the electrode A to the cover and also serve as outside electrical terminals for the anode as'indicated at 2|.

The cover l4 rests on a circular indent l5 of the container 29 and is provided with a nipple it having a vent hole is to vent the gases developed during operation of the devices.

The top of the cover I4 is provided with a peripheral recess to receive a sealing gasket ll around which the free end of the container 20 is spun. This provides for an air-tight seal between the cover and the container.

On its bottom, the cover I4 is provided with an annular collar 20 and a cylindrical recess 21 within said collar. A gasket 23 preferably of soft rubber and a metal washer 22, preferably of film-forming metal as aluminum, surround the stem II and are disposed within the recess 21. when the electrode A is screwed against the cover ll by means of the nuts l2l2', the stem shoulder 2| presses the metal washer 22 against the gasket 22, causing the latter to be compressed in the direction of the pressure and to expand in the direction perpendicular thereto thereby forming a tight seal preventing leakage or creepage between the stem and the cover.

While such Joint is extremely simple, convenient in assembly and requires only few and inexpensive parts, it has been found to give far better results than all sealing means used so far in the art for similar purpose.

It should be of course understood that besides preventing leakage between the electrodes and the cover; it is of equal importance to prevent leakage along other joints which may exist in the electrolytic device. For instance, in the case illustrated, leakage should be also prevented between the nipple IO and the cover I4 and for this purpose it is preferable if the nipple and cover are made of a single piece as proposed in the co-pending application of C. Shugg and P. Robinson, Ser. No. 451,029 filed May 8, 1930, now Patent No. 1,895,738, and it is equally important to prevent leakage between the container and the cover which is provided for by the means previously described.

While we have described our invention in a specific application and in a specific embodiment, we do not wish to be limited to such application or embodiment, but desire the appended claims to be construed as broadly as permissible in view of the prior art.

What we claim and desire to secure by Letters Patent is the following:

1. An electrolytic condenser comprising a cover of insulating material and an electrode provided with a stem projecting through the cover, a recess in said cover, an annular gasket and a flexible annular metal washer, both surrounding said stem and disposed in said recess, and means to fasten the stem to the cover, said fastening means also causing compression of the gasket to insurea liquid and air-tight seal between the stem and the cover.

2. In an electrolytic condenser, a cover of insulating material and an electrode of film-forming metal projecting therethrough, a gasket surrounding the electrode where it enters into the cover and contacting with the bottom of the cover, and a self-aligning annular washer of film-forming metal disposed under the gasket, and means to press the washer against the gasket and cause the gasket to spread, thereby insuring a liquid and air-tight seal which prevents leakage between the electrode and the cover.

3. In an electrolytic condenser, a cover and a film-forming electrode provided with a stem projecting through the cover, a shoulder on said stem, an annular metal washer of small thickness surrounding the stem and resting on the shoulder thereof, an annular gasket on top or the washer also surrounding the stem, said gasket contacting with the bottom face of the cover at the entrance oi. the stem, and means to press the shoulder against the washer and thereby spread the gasket so that the latter forms an air and liquid-tight seal preventing leakage of the electrolyte and creepage of the salt between the stern and the cover.

4. In an electrolytic device, a cover and an electrode having a stem, provided with a bevelled shoulder, projecting through the cover, a flexible annular metal washer surrounding the stem and engaging the bevellel shoulder, and an annular gasket on top of the washer also surrounding the stem, said gasket contacting with the cover where the stem enters the cover, and means to press the bevelled shoulder against the washer and thereby spread the gasket, so that the gasket constitutes an air and liquid-tight seal preventing leakage of the electrolyte and creepage of the salt between the stem and the cover.

5. In an electrolytic condenser, a cover of insulating material having an annular recess, a film-forming electrode and a supporting stem therefor, said stem being centrally located in said recess and projects through said cover, said stem having a beveled portion and a portion of reduced diameter above said bevelled portion, a flexible metal washer surrounding said stem and resting on said bevelled portion, and a sealing gasket resting on the metal washer and surrounding said reduced portion, said gasket being closely surrounded by the wall of said recess, and a member adapted to press the bevelled portion of the stem against the metal washer to uniformly compress said gasket.

6. In an electrolytic condenser comprising a container and an electrolyte therein, said container comprising a closure and an electrode 01 film-forming metal projecting through said closure, a flat gasket surrounding the electrode where it enters said closure, said gasket contacting with one face with said closure, a sell-aligning annular washer of film-forming metal contacting with the other face of said gasket, and means to press the washer against the gasket and cause the gasket to spread to insure a liquidand air-tight seal between said electrode and closure.

F. DESMOND SPRAGUE. FREDERICK W. MCNAMARA. 

